Printing roll



All@ 2 19381 M. M. sAFFoRD 2,125,817

l PRINTING ROLL v` Fileqsept. 11, 1931 His Abb ohngg.

yPatented Aug. 2, 1938 UNITED STATI-:svv

2.125317 PRINTING non.

Moyer M. Salford, Schenectady, N. Y., assignor to General ElectricCompany, a. corporation of New York Application September 11, 1931,`Serial No. 562,353 s claims. V(ci. en -sms) The present inventionrelates to printing rolls.

A principal object of the invention is to produce an improved printingroll which will be oil resistant, will not cause distortion of thecharacters being printed and have longer life than the present printingroll constructions.

Other and further objects of the invention will be more apparent as thedescription thereof proy ceeds. l0 In the printing industry it is oftenrequired to transfer printing from an embossed metal roll to a rubbercovered roll which in turn transfers it to paper or some other material.After these rubber rolls have been in usefor a short period of time theyabsorb oil from the ink causing distortion which in turn causesinaccurate printing. The rubber covered rolls or rolls made of glycerineand glue compositions which are also used in the printing industry areparticularly alected in hot weather and by friction. The rolls must bekept resilient and of the proper consistency suitable to the season sothat rolls made for winter use cannot be successfully used in warmweather and vice versa. Present types of rolls have short life and inindustries where considerable printing is done, as for example in thenewspaper industry, frequent changing of rolls especially in hot weatheris necessary in order to i prevent delay in operations,

In accordance with the present invention a` printing roll has beenconstructed wherein the surface is made of a material, which likerubber, is resilient and iiexible, but unlike it does not absorb oil,does not soften appreciably or melt in hot weather or under friction,but retains its iiexibility and resiliency, thus permitting accuratereproduction of characters being printed and which results in a printingroll having longer life than printing rolls of present construction.

For a consideration of what is believed to be novel and the invention,attention is directed to the following specification, in connection withthe accompanying drawing, and the claims appended thereto.

The drawing illustrates somewhat diagrammatically the various steps inthe process of making the printing roll as well as the finished product.Inv the drawing, Fig. 1 is-a view in perspective showing the roll in apreliminary stage of construction carrying a surface sheet of alkydresin and ready for the mold. Fig.V 2 is a perspective view partlybroken away showingthe moldcontaining the vroll illustrated g in Fig.1.. Fig. 3 is a view partly in elevation and partly in section showingthe roll held in place by specially constructed means to permit propercuring of the same, and ready for the oven treatment which follows.

Fig. 4 is a perspective view of the finished product, and

Fig. 5 is a view in perspective of a slightly modified form of the roll,

In carrying the invention into practice a roll is constructed whereinthesurface is of a exible type of alkyd resin. Asis known, alkyd resinsinclude all those complexes resulting primarily from the interreactionof a polyhydric alcohol such as glycerine, and a polybasic acid or itsanhydride, such as phthalic anhydride. These resins may be prepared invarious degrees of exibility, the flexibility being permanent incharacter. Such resins are more fully described and claimed in thecopending application of R. H. Kienle and H. C. Rohlfs, Serial'No.393,119, filed Sept. 16, 1929 now Patent No. 1,897,260 dated Feb. 14,1933 and assigned to the same assignee as the present invention.Briefly, the resins are prepared by reacting suitable proportions ofdibasic aliphatic acid, for example succinic or adipic acid, anddihydric alcohol, for example, ethylene glycol, with the usual alkydresin ingredients,

namely, a polyhydric alcohol having preferably l three or more hydroxylgroups in the molecule,

for example, glycerine, and a polybasic aromatic `acid or its anhydridefor example, phthalic anhydride. By varying the ratio of dibasicaliphatic acid-dihydric alcohol ester to polyhyric alcohol-polybasicacid ester the degree of ilexibility of the resinous compositions may bevaried. Increasing, for example, the ratio of the former to the latterincreases the exibility of the resulting resin.

As an example of the preparation of a resin suitable for use in theconstruction of the printing roll of the present invention the followingis given.

Glycerine, phthalic anhydride, ethylene glycol and succinic acid aretaken in proportions such that the ratio of glycol succinate to glycerolphthalate is 4:1. The ingredients are heated together in an aluminumvessel to a temperature of 180-200 C. until there is evidence ofgelation. The melt is then poured into shallow amalgamated tins andcured at about C. or higher from about three to five weeks. The curedresin is tough, resilient and exceedingly flexible under all conditions.

In constructing the printing roll a suitable body portion or core I0 isiirst taken. This body por- 55 tion may be of any material suitable as acore material for receiving the alkyd resin layer. Por example, it maybe constructed of steel. On this core is placed a layer or sheet Il ofthe flexible resin, the resin being wrapped around the core and Joinedat the meeting edges. In order to prepare this sheet of resin thefollowing procedure is satisfactory:

A composition which is by weight '15% completely cured, 4:1 resinprepared as outlined above is broken down on ordinary rubber compoundingrolls into a fine i'lour consistency and is mixed with 25%.oftwenty-four hour-cured 4:1 resin. After working the mixture on thecompounding rolls for a period of time the mass is formed into arubber-like sheet. Such fillers as cork, wood ilour, cotton flock,lamp-black, titanium dioxide and the like may be incorporated with theresin, although the pure resin is entirely satisfactory. In order tohave a dense material for molding the composition is next placed betweendat steel chromium plated plates and pressed under heat into a flatsheet of about thickness. The plates are then cooled and the sheetremoved. This is the sheet Il enveloping the core Il.

The mold l! shown in Pig. 2 1s an aluminum split mold provided with endplates I3 removably secured thereto as by screws Il. 'nie mold is linedwith brass tubing (not shown) and is chromium plated on its innersurfaces. It is designed to hold the core I of the printing roll and thesheet of resin Il wrapped thereon as clearly shown in Fig. 2. After thecore wrapped with the alkyd resin has been inserted in the mold the moldis closed and allowed to heat, then pressure is applied. Holes I5 areprovided in the end plates of the mold through which excess resin mayextrude as pressure is applied. Pressure is applied very slowly untilthe mold has been closed. A pressure of for example 1500-2000 pounds persquare inch at a temperature of about 150 C. is satisfactory. After ashort time, about minutes, under heat and pressure, the mold is cooled,preferably under pressure, after which the roll is removed. At thisstage the roll is considerably over size and the layer of resin is stillnot totally cured. It is well to mention that the inner surfaces of themold should be adequately covered with a material such as a mixture ofsoap and mica powder to prevent sticking upon extraction of the rolltherefrom.

The roll is now ready for the curing operation. 'I'his operation is animportant step in the process. In order to successfully cure the sheetof resin and at the same time have it keep its shape it has beennecessary to provide special means for clamping or holding the rollwhile the curing operation takes place. In Fig. 3 this means for holdingthe roll in place is shown. The roll taken from the mold is iirstclamped between end plates i6 and i1 held in place by means of a rod I8passing through the center of the core I0. The rod i8 is fixed to theend plates by nuts I9 and 20, screwed on the threaded ends thereof. Aswill be apparent later, the object of these end plates is to prevent theresin which is still in the plastic stage from being forced over theends when wound with tape and wire.

'I'he end plates being in place and the roll clamped therebetween, asingle layer 2i of medium weight cloth tape is wound as tightly aspossible over the the whole roll. I'he purpose of this tape is to allowgases generated during curing of the resin to be expelled and at thesame time to arcani? prevent the layer of cord or wire which will coverthe surface from sinking into the roll.

After the roll has been covered with tape it is then wound tightly witha single layer 22 of strong cord or wire. preferably wire, and of say 40mil dimension. 'Ihe unit is now placed in a suitable oven, preferablyone which is electrically heated, and maintained at a temperature of 140C. for a period of twenty-four to ninety-six hours depending on thedegree oi' hardness desired in the resin surface. After ninety-six hourscomposition has reached the maximum hardness for a 4:1 type ofcomposition.

When the roll has been cured for the requisite period of time it isremoved from the oven and allowed to cool slowly. The surface is thenmachined to size on a lathe using preferably a cutting speed of about250 revolutions per minute and a feed of about 100 turns per inch. Apointed nose tool having a large rake is satisfactory for this purpose.A smooth surface is thus 'obtained. An extremely smooth surface can beobtained by providing the surface while machining with emery our andwater.

In Fig. 4 thc finished roll 23 is shown, embodying the core Il, and thefinished alkyd resin surface 24 on the core.

Fig. 5 shows a slightly modified form of construction wherein there isinterposed between the core l0 and alkyd resin layer, a sheet or layer2i of a resilient material adapted to increase the cushioning orresiliency of the roll. In some cases such a construction may bedesirable, as for example in the construction of the cushioning roll inthe impression type of rolls. Among suitable resilient materials forthis purpose may be mentioned rubber, compositions of cork, gelatin. oroxidized oils, or suitable compositions of such materials. In some caseswhere an intermediate layer of resilient material is employed it may bepractical to provide the layer with a surface of flexible alkyd resin byapplying thereto a suitable lacquer embodying .such resin or a layer ofthe flexible resin may be directly cast either on the core itself or onthe intermediate layer 25. At present, however, I prefer theconstruction shown in Fig. 4 made as described in detail in theforegoing specification.

While the preferred resin composition is one wherein the ratio ofdibasic aliphatic aciddihydric alcohol ester to polyhydricalcoholpolybasic acid ester is 4:1, this ratio is not the only one whichmay be employed. Successful combinations for the purpose intended may bemade by varying the ratio between the limits 2:1 to 8:1.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is,-

1. A printing roll comprising a steel core surfaced with a flexibleresilient, non-oil-absorbent, printing ink resistant alkyd resin, saidresin being the product of reaction of glycerine, phthalic anhydride,glycol and succinic acid.

2. A printing roll comprising a core and a surface layer on said corecomprising the product of reaction of a polybasic aromatic acid,polyhydric alcohol having three or more hydroxyl groups in the molecule,a dihydric alcohol and a dibasic aliphatic acid, said surface layerbeing resilient, non oil-absorbent and printing ink resistant.

3. A printing roll provided with a surface layer of non-oil absorbent,printing ink resistant, resilient resin, said resin being the product ofreaction of glycerine, phthalic anhydride, a dihydric alcohol and adibasic aliphatic acid.

4. A printing roll comprising a core. an intermediate layer of resilientmaterial and a surface layer of non-oil absorbent, printing inkresistant alkyd resin in the permanently exible and resilient state,said resin being the product of reaction of glycerineI phthalicanhydride, a dihydric alcohol and a dibasic aliphatic acid.

5. A printing roll comprising a metallic core and a printing surfacefixed on said core, said printing surface comprising a layer ofpermanently flexible, oil-resistant alkyd resin comprising the curedproduct of a mixture ot completely cured and partially cured products ofreaction of glycerine, phthalic anhydride, dihydric alcohol and dibasicaliphatic acid.

MOYER M. SAFFORD.

